We propose to establish a center focused on the development of field deployable physical biodosimetry utilizing EPR measurements of teeth and nails through three synergistic projects and highly integrated cores based on prior progress. The rationale for our approach we believe is compelling though relatively simple. 1. In order to respond adequately to a radiation incident in which large numbers of individuals potentially have received doses of radiation that could lead to the acute radiation syndrome it is essential to determine the dose to individuals rapidly and accurately. 2. The current capabilities and guidelines are not adequate for doing this. 3. The dosimetry system should be based on radiation induced changes within the individual so that a dosimeter is always in place, i.e. biodosimetry is needed. 4. Biologically based biodosimetry, while potentially very valuable, inherently must have ambiguity because it depends on the activation of responses to injury that are not specific for ionizing radiation, must vary in time as the responses are developed and later attenuated, and are very likely to be affected by both pre-existing conditions and concurrent perturbations such as stress, wounds, and burns. 5. Physical biodosimetry does not have the potential limitations of the biologically based biodosimetry. 6. EPR dosimetry based on radiation-induced changes in teeth and nails is the most advanced physical biodosimetric technique and has been shown to be capable of resolving doses in the range of interest with immediate readout. 7. Our group has led the development of such EPR dosimetry and is poised to make it into a field deployable technique that can be implemented by non-expert operators without any prior training. We will complete the development of the techniques and construct field-deployable prototypes of instruments based on three different and complimentary approaches: measurements in vivo in teeth, measurements in vivo in nails, and measurements in vitro on clipped fingernails. We expect these applications to be part of a multimodality approach to field dosimetry, complementing biological biodosimetry. We have potential commercial partners, especially General Electric, who is prepared to use the prototypes to carry out rapid FDA-compliable production of fully deployable versions as soon as the prototypes are available from the proposed center.